A sealing device for a rolling bearing according to prior art is disclosed in JP 2006-118625 A (Patent Literature 1).
Reference sign 100 in FIG. 4 generally denotes a rolling bearing for supporting a wheel in a rotatable manner, which is composed of an outer ring 101, an inner ring, 102, and, a number of steel balls 103 placed between the rings and arrayed in a circumferential direction of the bearing.
The sealing device for the rolling bearing is intended to prevent muddy water, dust and the like from entering from the outside into the inside of the rolling bearing 100 and to prevent grease for lubricating the steel balls 103 from flowing out of the bearing. The sealing device includes a slinger 113 which is composed of a sleeve 111 fitted around an outer peripheral surface of the inner ring 102 and a seal flange 112 extending radially from one axial end of the sleeve 111 at a generally right angle relative to a shaft center, and an attachment ring 120 fitted around an inner peripheral surface of the outer ring 101. The sealing device also includes an outer peripheral side seal lip 121 and an inner peripheral side seal lip 122, which are integrally provided on the attachment ring 120, abutted against the seal flange 112 of the slinger 113 in a slidable manner and are concentric with each other. Also, the sealing device includes a labyrinth lip 123 provided integrally with the attachment ring 120 and facing an outer peripheral surface of the sleeve 111 of the slinger 113 in a non-contact manner, and a gasket section 124 provided integrally with the attachment ring 120 and in contact with the inner peripheral surface of the outer ring 101.
The slinger 113, which is manufactured by punch pressing of a metal plate such as a sheet steel, is composed of, as described above, the sleeve 111 press fitted around the outer peripheral surface of the inner ring 102 of the rolling bearing 100, and the disc-like seal flange 112 extending radially at an end portion of the bearing toward the outer peripheral side of the bearing, orthogonally to the shaft center. More specifically, the slinger 113 has a generally L-shaped cross section taken along a plane containing the shaft center.
In the slinger 113, with an axially inner part of the sleeve 111 (a part of the sleeve opposite from the seal flange 112) press fitted around the outer peripheral surface of the inner ring 102, the sleeve 111 radially expands in an elasticity range and causes stress in the inner ring 102. Further, with an axially outer part of the sleeve 111 (i.e., a part of the sleeve adjacent to the seal flange 112) press fitted around the outer peripheral surface of the inner ring 102, large stress is caused in the inner ring 102 by the effect of radial rigidity of the seal flange 112. Consequently, the inner ring 102 deforms, and as a result of contraction of the inside diameter of the inner ring, the inside diameter of the inner ring 102 becomes smaller than a specified diameter, thereby causing a problem of the inner ring 102 having an irregular inside diameter.
Moreover, with the axially outer part of the sleeve 111 (i.e., the part of the sleeve 11 adjacent to the seal flange 112) press fitted around the outer peripheral surface of the inner ring 102, the seal flange 112 is deformed to be inclined toward the axial outside of the bearing, thereby causing damage on sealing performance.